The present invention provides an improvement in the Lock Cylinder Cover With Key Engagement Release of U.S. Pat. No. 3,930,391 issued to Hans J. Borlinghaus Jan. 6, 1976 and assigned to the Assignee of this invention.
According to the Borlinghaus patent, a lock cylinder cover arrangement includes an escutcheon having an opening registering with the lock cylinder and a cover which is pivotally mounted on the escutcheon and is biased by a spring to a closed position covering the lock cylinder. A spring detent secured to the underside of the escutcheon includes a resilient arm having a stop surface which bears against the underside of the cover until pivotal movement of the cover to the fully open position permits the resilient arm to spring outwardly and engage the stop surface with a shoulder of the cover to hold the cover in the open position enabling the insertion of a key into the lock cylinder. The resilient arm also has a cam surface which the outward movement of the resilient arm poises in the path of unlocking rotation of the key so that the key engages the cam surface and cams the resilient arm inwardly to thereby release the stop surface from engagement with the shoulder of the cover so that the cover is first spring biased into engagement with the key and then subsequent removal of the key from the lock cylinder permits the cover to move to the fully closed position.
A shortcoming of the aforedescribed lock cover release arrangement is that under some circumstances the mechanism can be tricked to continue its hold-open of the cover in the open position even after the key has been rotated and then subsequently withdrawn from the lock cylinder. For example, it has been observed that gloves worn by a vehicle operator may inadvertently hold the cover in the open position during the unlocking rotation of the lock cylinder and during the subsequent counter rotation of the lock cylinder to its normal position after being unlocked so that the resilient arm is moved inwardly but then returns axially outwardly to return the stop surface into engagement with the shoulder of the cover, thereby re-establishing the hold-open retention of the cover in the open position. This same condition can occur when a vehicle operator unfamiliar with the attributes of the Borlinghaus invention uses his one hand to hold the escutcheon open while the other hand rotates the key.
The present invention provides an improvement to the Borlinghaus key engagement release arrangement which will assure that the resilient arm of the cover hold open detent spring will be retained at its inward release position reliably until the cover is moved sufficiently in the closing direction to prevent a re-engagement of the stop surface with the cover by the integral resilient action of the resilient arm.